Conveyor belts often come in relatively large widths, for example, 24, 48, 60 or more inches in width. The belts are often troughed so that the longitudinal sides of the belt are canted upwardly and outwardly from a lower central section to contain the conveyed material so as to prevent the material from falling off the sides of the belt. Commonly used hinged belt fasteners are joined to opposite ends of the belt, and hinge loops are interdigitated to form a common bore into which is inserted a hinge pin that prevents the hinge loops from separating. The hinge loops exert transverse shear forces on the elongated pin, which is in one piece when inserted into the bore. When the belt is troughed, the flexible hinge pin, which is often a length of flexible cable, bends at the locations of the canted side sections and the lower center section of a troughed belt. These cable-like hinge pins are constructed to withstand large, tensile loads; but when used as hinge pins, are subject to transverse shear loads to which the cable is not well suited. The transverse loads from the belt loops tend to cut or wear grooves in the hinge pin at the hinge loop locations across the splice section that usually preclude a removal of the hinge pin after it has been in use for a while.
The troughed hinge pin usually breaks into at least three pieces with the center piece being difficult to remove. Often the ends of the hinge pins are struck by equipment or otherwise damaged so that there is not a good end to grip to pull the hinge pin from the loops of the interdigitated belt fastener loops. Even if there is a good end to grip and the pin is broken, only the outer end section will be gripped and pulled. Thus, it is often necessary to cut the belt fasteners off the belt end when a hinge pin cannot be removed. Accordingly, the conventional cable hinge pin used with hinge-type belt fasteners is not easy to replace when it has been in use for a while.
Often in coal mines or in material handling applications, the belt length is desired to be changed relatively frequently either to make the belt longer or to make it shorter. Usually, a section of belt is either added or subtracted. This belt section is usually connected by hinge belt fasteners with a flexible hinge cable-type pin which, if broken, is very difficult, if not impossible, to remove. Thus, there is a need to provide an improved hinge pin replacement.
The belt fasteners are hinged as the endless belts are wrapped about pulleys or drums when travelling from an upper run to a lower run. For example, the belt fasteners travel about a nine inch diameter drum, and are expected to fit the curve of such a diameter much in the manner that the belt does.
A particular problem that needs to be addressed with these types of belt fasteners is that of preventing sifting of fines or fine particulate through the splice formed by the belt fasteners and the hinge pin. Thus, the hinge pin replacement should not be such an open device that fines fall readily through the splice. Also, belt scrapers often scrape the top of the conveyor belt, and the hinge pin replacement should not be damaged by such scrapers as it passes by the scrapers. The material being conveyed is often very abrasive, and the hinge pin replacement should be capable of withstanding abrasion or wear.
Solid rod hinge pins have been used rather than the flexible, cable hinge pins, with the solid rod hinge pins extending through the passageway defined by the overlapping fastener hoops. However, the solid rods have been found undesirable since they do not provide the requisite flexibility necessary to flex a belt across its width to form a trough, as required in many conveyor belt applications.